University of Nebraska - Lincoln
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Agronomy & Horticulture -- Faculty Publications
Agronomy and Horticulture Department
1969
Physiological Aspects of Crop Yield (Frontmatter)
Jerry D. Easton
University of Nebraska-Lincoln
Francis A. Haskins
University of Nebraska-Lincoln, [email protected]
C. Y. Sullivan
University of Nebraska-Lincoln
C. H. M. Van Bavel
Texas A&M University
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Easton, Jerry D.; Haskins, Francis A.; Sullivan, C. Y.; and Van Bavel, C. H. M., "Physiological Aspects of Crop Yield (Frontmatter)"
(1969). Agronomy & Horticulture -- Faculty Publications. 191.
http://digitalcommons.unl.edu/agronomyfacpub/191
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Published in Physiological Aspects of Crop Yield: Proceedings of a symposium
sponsored by the University of Nebraska, the American Society of Agronomy, and the
Crop Science Society of America, and held at the University of Nebraska, Lincoln, Nebr.,
January 20-24, 1969. Edited by Jerry D. Eastin, F. A. Haskins, C. Y. Sullivan, C. H.
M. Van Bavel, and Richard C. Dinauer (Madison, Wisconsin: American Society
of Agronomy & Crop Science Society of America, 1969). Copyright © 1969
American Society of Agronomy & Crop Science Society of America. Used by
permission.
PHYSIOLOGICAL ASPECTS
OF CROP YIELD
Proceedings of a symposium sponsored by the University of Nebraska,
the American Society of Agronomy, and the Crop Science Society of
America, and held at the University of Nebraska, lincoln, Nebr., January 20-24, 1969. Financial support for the symposium came from The
Rockefeller Foundation. Publication assistance was provided through
the International Biological Program.
Editorial Committee
JERRY D. EASTIN, Chairman
Plant Physiologist, Cereal Crops Research Branch, Crops Research
Division, Agricultural Research Service, US Department of Agriculture, and Associate Professor, Department of Agronomy, University
of Nebraska, Lincoln. Nebraska.
F. A. HASKINS
Professor, Department of Agronomy, University of Nebraska,
Lincoln, Nebraska
c. Y. SULLIVAN
Associate Professor, Department of Horticulture and Forestry,
University of Nebraska, Lincoln, Nebraska
c. H. M. VAN BAVEL
Professor, Institute of Life Sciences, Texas A & M University,
College Station, Texas
Managing Editor: RICHARD C. DINAUER
Published by
American Society of Agronomy
Crop Science Society of America
Madison, Wisconsin USA
1969
Copyright © 1 ~JG9, by the American Society of Agronomy, Inc., and
the Crop Science Society of American, Inc., G77 South
Segoe Road, Madison, Wis. 53711 USA
ALL RIGHTS RESERVED.
No part of this book may be reproduced in any form, by
photostat, microfilm, or any other means, without written
permission from the publisher.
Library of Congress Catalog Card Number:
Printed in the United State of America
76-~)4;n6
FOREVVORD
This volume is the outgrowth of an international symposium held at
Lincoln, Nebraska, January 20-24, 1969. It was sponsored by the University of Nebraska in cooperation with the American Society of Agronomy and the Crop Science Society of Ameriea with partial financing by
the Rockefeller Foundation and the International Biological Program.
The symposium planning committee was broadly based and was able
to bring specialists from many parts of the world to the conference.
Thus, the technical presentations were drawn from outstanding authorities backed up by a clear perspective of social needs. This was a happy
combination which contributed greatly to the success of the conference
and is shown on the printed pages of this book. Happy, too, is the realization that in this symposium the most basic of inquiry into the physiology of plants is brought to bear on solving problems of the yield of
economic plants vital to man's existence, both now and in the long view
ahead. Empiricism, successful in past decades will, we are convinced,
be augmented and in some cases be replaced by the new understanding
of the physiology of yield in plants.
We sometimes hear that research is less enjoyable and rewarding
now than formerly, partly because it is so fragmented. The output is
so great that no one can keep up with more than a mere fraction of research reports and relating one part with another is often difficult. We
believe the symposium presented here in book form has bridged some of
these chasms.
There is no reason why science cannot be put to work somewhere to
assist man in his eternal quest to control his environment and satisfy
his basic needs and ambitions. However, there are many examples of
misguided or abortive "advances" which produce short-term or local
gains at the risk of much larger long-term losses. Hence, as was
brought out at the symposium, a certain level of technology must be
evaluated in terms of its cost, its worth, and the goals men hold. The
societies which sponsored this undertaking are dedicated to the encouragement of excellent science and to the dissemination of knowledge. We
believe this book represents a positive and useful effort toward both.
July 1969
L. P. Reitz, President, CSSA
W. L. Nelson, President, ASA
v
PREFACE
Mounting world population pressures and accompanying malnutrition problems pose grave concerns in the minds of thoughtful men. The
nature, scope, and impending gravity of this situation has been ably
characterized by Dr. J. J. Harrar, President of the Rockefeller Foundation. In a stimulating address during the symposium, Dr. Harrar identified the two principal approaches toward alleviating malnutrition as
(i) increased food production per unit land area and (ii) population control. This symposium was concerned with the first approach.
Despite the considerable genetic sophistication incorporated into
current plant breeding techniques, C. M. Donald describes plant breeding approaches as being largely empirical (Advances in Agronomy, Vol.
15) because our knowledge and use of yield-related physiological and
morphological characters is meager. Crop physiologists and biochemists must continue to provide plant breeders with criteria for tailoring
crops to different environments, and plant breeders in turn must recognize and use these criteria in their programs.
Plant production processes must be better understood if maximum
economic yields are to be realized and exploited. The competitive advantage of any biologic organism in the field, be it crop plant or pest,
is dictated by its relative response to the prevailing environment. Environmental physiology research has scarcely touched on interdependencies amongst and control of the major physiologic processes dictating
competitive advantage. Quantitating the environment and plant morphologic characters simultaneously with major physiologic process rates
may provide much essential perspective concerning the order of these
yield limiting factors. The subsequent exploitation of these yieldrelated factors will depend on their detailed characterization at cellular
and molecular levels.
Life processes, in the final analysis, are the sum total of biochemical reactions at cellular and molecular levels. The manner in which
these reactions interrelate dictates the efficiency with which light energy
is trapped in the plant, converted to chemical energy, and elaborated
into storage products useful to man. A significant, increased rate of
progress in breeding for yield will depend on expanded, interrelated
advances in disciplines such as environmental physiology, systems
analyses, simulation and bioinstrumentation, anatomy and morphology,
cell biology, and genetics. This symposium was keyed to reviewing and
highlighting selected aspects of knowledge in some of these diverse disciplines in an attempt to br;dge some of the gaps between essential field
and molecular level research pertaining to higher crop yields.
The Rockefeller Foundation approved a five-year grant in 1966 to
the Nebraska Agricultural Experiment Station in support of a research
program entitled "The Physiology of Yield and Management of Sorghum
in Relation to Genetic Improvement." A sum was included in the grant
budget to assist in financing a symposium concerning the application of
physiological principles in the improvement of crop yields.
vii
viii
PREFACE
Arrangements were made for the American Society of Agronomy
and the Crop Science Society of America to cooperate with the Universityof Nebraska in sponsoring the symposium. The symposium planning
committee members were Drs. F. A. Haskins (chairman), J. M. Daly,
Jerry D. Eastin, and C. Y. Sullivan, representing the University of
Nebraska and appointed by Dr. H. W. Ottoson, Director of the Nebraska
Agricultural Experiment Station; Dr. C. H. M. van Bavel, representing
the ASA, appointed by Dr. R. S. Whitney, then President of the ASA; and
Dr. R. W. Howell, representing the CSSA, appointed byDr. A. A. Hanson,
then President of the CSSA.
The symposium was held from January 20 to 24, 1969, at the Nebraska Center for Continuing Education, as one of the first events in
the Centennial observance of the University of Nebraska. Registration
at the symposium totalled approximately 445 persons. A total of 40
states and the D;istrict of Columbia in the USA, and 14 countries outside
the USA were represented at the conference.
A complete listing of all those who have helped the planning and
editorial committees is not feasible. However, the committees do wish
to acknowledge publicly the excellent contributions of all speakers, invited discussants, and session chairmen. The names of the speakers
and of those invited discussants who elected to submit copy for this
volume are shown in the Table of Contents. Two of the invited discussants made excellent verbal presentations but chose not to submit copy
for publication. They were Drs. C. B. Tanner, University of Wisconsin,
and V. T. Walhood, ARS, USDA. One of the invited discussants, Dr.
R. W. Allard, University of California, Davis, was unable to attend the
symposium.
Chairmen of the eight half-day sessions were the following: Dr.
H. H. Kramer, Purdue University; Dr. D. E. McCloud, University of
Florida; Dr. C. H. M. van Bavel, Texas A and M University; Dr. G. E.
van Riper, Deere and Company; Drs. R. W. Howell and F.G. Viets, ARS,
USDA; and Dr. E. F. Frolik and H. W. Ottoson, University of Nebraska.
The contributions of the following in various phases of planning and
conducting the symposium and/or publishing this volume also merit
special mention:
Drs. Sterling Wortman and Lewis M. Roberts of the Rockefeller
Foundation
Dr. A. B. Ward of the Nebraska Center for Continuing Education
Drs. D. C. Smith and F. L. Patterson, Past-Presidents of the ASA
and CSSA, respectively
Drs. W. L. Nelson and L. P. Reitz, Presidents of the ASA and CSSA,
respectively
Dr. Matthias Stelly and Mr. R. C. Dinauer of the ASA Hdqtrs. staff
The financial support of the Rockefeller Foundation has already
been mentioned. Without it, this symposium would not have been possible. The financial contribution of the International Biological Program
toward the publication of this volume also is acknowledged with thanks.
July 1969
The Editorial Committee: Jerry D. Eastin (chairman); F. A. Haskins;
C. Y. Sullivan; C. H. M. van Bavel.
CONTRI BUTORS
Donald N. Baker
Soil Scientist, Soil and Water Conservation Research Division, Agricultural Research Service, U.S. Department of Agriculture, Boll Weevil Research Laboratory,
State College, Mississippi
Harry Beevers
Professor of Biology, Department of Biological Sciences, Purdue University, Lafayette, Indiana
Or lin Biddulph
Professor of Botany and Director of Molecular Biophysics Laboratory, Washington State University, Pullman, Washington
Robert F. Chandler, Jr.
Director, International Rice Research Institute, Manila, Philippines
Marion Clawson
Director, Land Use and Management Program, Resources for the Future, Inc.,
Washington, D.C.
Harry F. Clements
Senior Plant Physiologist, Emeritus, and
Consulting Plant Physiologist, Retired,
Hawaii Agricultural Experiment Station
and C. Brewer and Company, Ltd., Honolulu, Hawaii
Alden S. Crafts
Professor of Botany, Emeritus, Botany
Department, University of California,
Davis, California
O. T. Denmead
Senior Research Scientist, Commonwealth
Scientific and Industrial Research Organization, Canbe'rra, Australia
William G. Duncan
Professor of Plant Physiology, Department of Agronomy, University of Kentucky,
Lexington, Kentucky
Pieter Gaastra
Doctor, Centre for Plant Physiological
Research, Wageningen, The Netherlands
Norman E. Good
Professor of Plant Biochemistry and Physiology, Department of Botany and Plant
Pathology, Michigan State University,
East Lansing, Michigan
ix
x
CONTRIBUTORS
Richard H. Hageman
Professor of Crop Physiology, Department
of Agronomy, University of Illinois, Urbana, Illinois
John B. Hanson
Professor of Plant Physiology, Department of Botany, University of Illinois, Urbana, Illinois
John Heslop-Harrison
Professor, Institute of Plant Development,
University of Wisconsin, Madison, Wisconsin
Yoshiaki Ishizuka
Dean, Faculty of Agriculture, Hokkaido
University, Sapporo, Hokkaido, Japan
Peter R. Jennings
Leader, Inter-American Rice Program,
Centro Internacional De Agricultura Tropical, Colombia, South America
Neal F. Jensen
Professor of Plant Breeding, Department
of Plant Breeding and Biometry, Cornell
University, Ithaca, New York
Dov Koller
Professor, Department of Botany, The
Hebrew University of Jerusalem, Israel
(formerly Visiting Research Professor,
Laboratory of Nuclear Medicine and Radiation Biology, University of California,
Los Angeles, California)
Paul J. Kramer
Professor, Department of Botany, Duke
University, Durham, North Carolina
George G. Laties
Professor, Department of Botanical Sciences, University of California, Los Angeles, California
Edgar Lemon
Research Soil Scientist, Microclimate Investigations, Soil and Water Conservation
Research Division, Agricultural Research
Service, U.S. Department of Agriculture,
Cornell University, Ithaca, New York
R. S. Loomis
Professor, Department of Agronomy and
Range Science, University of California,
Davis, California
Walter E. Loomis
Formerly with Southern Illinois University, Carbondale, Illinois (now Professor
of Botany, Department of Botany, Iowa
State University, Ames, Iowa)
CONTRIBUTORS
xi
K. J. McCree
Associate Professor, Institute of Life Science, Texas A & M University, College
Station, Texas
Terence A. Mansfield
Doctor, Department of Biological Sciences,
University of Lancaster, United Kingdom
John Lennox Monteith
Professor, School of Agriculture, University of Nottingham, Sutton Bonington,
Loughborough, United Kingdom
Dale N. Moss
Professor, Department of Agronomy and
Plant Genetics, University of Minnesota,
St. Paul, Minnesota
Yoshio Murata
Head, Division of Plant Physiology, National Institute of Agricultural Sciences,
Konosu, Saitama, Japan
Werner L. Nelson
Senior Vice President, American Potash
Institute, West Lafayette, Indiana
J. J. Oertli
Associate Professor of Soil Science, Department of Soils and Plant Nutrition,
University of California, Riverside, California
John R. Philip
Chief Research Scientist, Commonwealth
Scientific and Industrial Research Organization, Canberra, Australia
Ralph O. Slatyer
Professor of Biology, Research School of
Biological SCiences, Australian National
University, Canberra, Australia
George F. Sprague
Research Agronomist, Crops Research
Division, Agricultural Research Service,
U.S. Departm.ent of Agriculture, Plant Industry Station, Beltsville, Mary land
Volkmar Stoy
Doctor, Swedish Seed Association, Svalof,
Sweden
Carroll Arthur Swanson
Professor of Plant Physiology, Faculty of
Organismic and Developmental Biology,
Ohio State University, Columbus, Ohio
Akira Tanaka
Professor of Plant Nutrition, Faculty of
Agriculture, Hokkaido University, Sapporo, Japan
xii
CONTRIBUTORS
J. W. Tanner
Professor, Department of Crop Science,
Ontario Agricultural College, University
of Guelph, Guelph, Ontario, Canada
Gillian N. Thorne
Doctor, Rothamsted Experimental Station,
Harpenden, Herts, United Kingdom
E. Bruce Tregunna
Assistant Professor, Botany Department,
University of British Columbia, Vancouver, British Columbia, Canada
Paul E. Waggoner
Chief Climatologist, The ConnecticutAgricultural Experiment Station, New Haven,
Connecticut
William A. Williams
Professor of Agronomy, Department of
Agronomy and Range SCience, University
of California, Davis, California
Israel Zelitch
Head, Department of Biochemistry, The
Connecticut Agricultural Experiment Station, New Haven, Connecticut
CONTENTS
v
FOREWORD
PREFACE.
CONTRIBUTORS
1
vii
ix
Systems Analysis of Natural Resources and Crop Production
1
MARION CLAWSON
I. Requirements of Crop Production
II. Aspects of Natural Resources
A. Qualities of Nature.
B. Technology
C. Economics.
D. Goals .
III. Natural Resources and Their Use as Systems
IV. Some Examples
A. Water Quality .
B. Large Scale Desalting of Sea Water for Commercial
Agriculture
C. A New Crop Variety
Literature Cited
2
1
3
4
4
5
6
8
10
10
11
13
14
15
Engineering for Higher Yields
YOSHIAKI ISHIZUKA
Introduction
Changes in Rice Yield from 1000 A.D..
.
.
A Blueprint to Obtain 6 Tons/Ha of Brown Rice.
Engineering for Higher Yields.
A. Plant Type.
B. Translocation and Respiration
C. Techniques of Fertilizer Application
D. Minor Elements
E. Soils .
15
15
16
18
18
21
22
23
23
Productivity and the Morphology of Crop Stands:
Patterns with Leaves
27
I.
II.
III.
IV.
3
R. S. LOOMIS and W. A. WILLIAMS
I. Community Organization .
A. Density of the Vegetative Cover
B. Horizontal Patterns Among Leaves.
C. Vertical Separation of Leaves
xiii
28
28
29
31
xiv
CONTENTS
D.
E.
F.
G.
H.
Vertical Distribution of Leaves and Light Interception
Foliage Angle .
Stratified Analyses of Foliage Angle
Light Distribution Models .
Azimuthal Orientations.
1. Nonleaf Structures.
II. Relation of Canopy Morphology to Production
A. Simulations of Crop Productivity
B. Some Experimental Results
Acknowledgments
Literature Cited
4
32
33
34
36
40
41
42
42
43
45
45
Discussion
DONALD N. BAKER
48
Discussion
J. W. TANNER
50
Physiological Significance of Internal Water Relations
to Crop Yield
53
R.O.SLATYER
1. Introduction
II. Development of Internal Water Deficits.
.
.
.
.
.
III. Effects of Water Deficits on Some Physiological Processes.
A. Water Deficits and Growth Processes .
B. Water Deficits and Physiological Processes
1. Water Deficits and Water Transport.
2. Water Deficits and Nutrient Uptake .
C. Water Deficits, Protein Synthesis, and Nitrogen
Metabolism
D. Water Deficits, Photosynthesis, and Carbohydrate
Metabolism
IV. Effect of Water Stress on Grain Yield in Cereals
A. Water Stress and Inflorescence Development
B. Water Stress and Fertilization.
C. Water Stress and Grain Filling.
V. Conclusions
Acknowledgment
Literature Cited
5
53
54
56
57
59
60
60
61
66
71
71
75
76
78
79
79
Discussion
PAUL J. KRAMER
84
Discussion
J. J. OERTLI
85
Light Interception and Radiative Exchange in Crop Stands
89
J. L. MONTEITH
1. Radiation and Crops
89
xv
CONTENTS
II. Specification of the System.
A. Radiation .
B. Leaves
1. Geometry
2. Optics.
III. Measurement of Radiation in Crops
IV. Theoretical Principles.
A. Random and Nonrandom Foliage
B. Transmission in Foliage
C. Translucent Leaves
D. Incident Flux .
E. Sunlit Area
F. Longwave Radiation
V. Measurements.
1. Cotton.
2. Clover.
3. Kale
4. Maize .
5. Barley.
6. Beans .
7. Rice
8. Ryegrass
VI. Conclusions
Aclmow ledgments
Literature Cited
6
90
90
92
92
94
95
96
96
97
99
99
101
102
102
104
104
104
105
105
107
107
107
108
108
109
Discussion
K. J. MC CREE
111
Discussion
J. R. PHILIP
113
117
Gaseous Exchange in Crop Stands
EDGAR LEMON
r.
Problems of Measurement and Understanding .
A. Brief Review of Energy and Momentum Balance
Methods of Measuring Gaseous Exchange in Crop
Stands.
B. Some Weak Points in the Methods
1. The Heat Budget
2. The Momentum Budget .
II. Agronomic Usefulness of Micrometeorological Studies
A. As a Measuring Tool and the Pursuit of Understanding
1. Plant Growth
2. Used as a Tool to Pinpoint Critical PlantEnvironmental Interactions.
3. Model Building and Testing.
Literature Cited
11 7
118
121
121
121
127
127
127
129
134
136
Discussion
O.T.DENMEAD
137
Discussion
PIETER GAASTRA
140
xvi
7
CONTENTS
Mechanisms of Translocation of Plant Metabolites
143
OR LIN BIDDULPH
143
144
145
147
147
148
149
151
155
156
158
158
159
159
159
161
162
1. Introduction
Anatomy of the Phloem
Loading of the Phloem.
Materials Translocated
Linear Rate of Movement
Distribution
Radial Loss from the Phloem
Tangential Movement
Removal from the Phloem
Mechanics of Translocation
A. Temperature
B. Inhibitors .
C. Log Pattern
D. Water Movement
E. Bidirectional Movement
XI. Summary.
Literature Cited
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
8
Discussion
ALDEN S. CRAFTS
165
Discussion
C. A. SWANSON
167
169
Metabolic Sinks
HARRY BEEVERS
I. The Kinds of Metabolic Sinks .
II. Concentration Gradients and Sinks.
III. Metabolic Reactions in Sinks
A. Absorption of Sugars
B. Fate of the Entering Sugar.
C. Accumulation of Sugars and Starch at Sinks.
1. Absorption of Sugars at an Accumulating Sink
2. Starch Formation
IV. Interaction Between Source and Sink
Literature Cited
9
169
170
172
172
173
174
174
175
177
179
Discussion
J9HN B. HANSON
180
Discussion
GEORGE G. LATIES
182
Interrelationships Among Photosynthesis, Respiration, and
Movement of Carbon in Developing Crops
185
VOLKMARSTOY
I. Interdependence of Photosynthesis and Respiration.
185
CONTENTS
II.
III.
IV.
V.
10
xvii
A. Photosynthesis and Respiration in Individual Plants.
B. Photosynthetic Production and Respiratory
Consumption in Plant Communities.
The Influence of Metabolic Sinks on the Rate of
Photosynthesis
A. Experimental Evidence.
B. Possible Mechanisms to Explain Sink Action
Growth and the Distribution of Photosynthetic Products.
A. The Distribution Pattern
B. Regulation of the Flow of Assimilates .
The Dependence of Yield on Photo synthetic Activity.
Challenges for the Future
Literature Cited
185
189
190
190
191
193
193
194
195
196
197
Discussion
DALE N. MOSS
203
Discussion
GILLIAN N. THORNE
205
Mechanisms of Carbon Fixation and Associated
Physiological Responses
207
ISRAEL ZELITCH
I. Control of Stomatal Aperture by Specific Inhibition of
Guard Cell Activity
A. Control of Stomatal Opening in Light
B. Effect of Inhibitors of Stomatal Opening on the CO 2
Compensation Point
II. Differences in Photosynthetic Efficiency Among Species
A. The Carboxylation Reactions
B. Photorespiration and its Measurement .
C. The CO 2 Compensation Point
D. Net Photosynthesis in Atmospheres Low in Oxygen
E. The Glycolate Oxidase Reaction as a Source of C~ in
Photorespiration
F. Increasing Net Photosynthesis by Inhibition of
Glycolate Oxidation
III. The Relation Between Photorespiration and Net
Photosynthesi s
. . . . . . .
A. A Sensitive 14C-Assay of Photorespiration
B. Comparison of Turnover of CO 2 to the Quantity
Released in COa-Free Air in the Light .
C. Effect of Genetic Control of Photorespiration on Net
Photosynthesis.
Literature Cited
207
207
208
210
210
213
215
215
216
217
218
218
219
221
223
Discussion
DOV KOLLER
226
Discussion
T. A. MANSFIELD
231
xviii
11
CONTENTS
Physiological Responses to Nitrogen in Plants
235
YOSHIO MURATA
I. Introduction
II. Nitrogen and Formation of "Yield-Container"
A. The Number of Spikelets and Nitrogen
B. Effect of Nitrogen Topdressing for Increasing the
Capacity of "Yield-Container" .
C. The Number of Spikelets and LAI
D. Fertilization (Pollination) and Nitrogen.
III. The Amount of "Contents" in Relation to the Capacity
for Yield
IV. Production of Reserve Substances, Ripening, and Nitrogen
A. Accumulation of Organic Substances and Nitrogen
B. Ripening and Nitrogen.
C. Photosynthetic Activity, Respiratory Activity, and
Nitrogen
D. Root Activity and Photosynthetic Activity
V. Dry Matter and Grain Production Under Abundant
Nitrogen Supply
A. Disruption of Photosynthesis-Respiration Balance
B. Influence of Solar Radiation on Nitrogen Effect
C. Disturbance of Nitrogen Metabolism
D. Decrease of Root Activity
E. Translocation and Distribution of Substances and
Nitrogen
F. Nitrogen Response of Varieties.
VI. Conclusion
Literature Cited
12
235
235
235
237
237
239
240
241
241
243
244
246
247
247
248
249
250
251
253
255
256
Discussion
R. H. HAGEMAN
260
Discussion
AKlRA TANAKA
262
Plant Morphology and Stand Geometry in Relation to
Nitrogen
265
ROBERT F. CHANDLER, JR.
I. Introduction
II. Morphological Characteristics Associated with
Responsiveness to Nitrogen
A. Length and Thickness of Culm.
B. Width, Thickness, Length, and Uprightness of Leaves
C. Tillering Capacity.
D. Panicle Weight.
E. Grain-Straw Ratio.
III. Stand Geometry and Nitrogen
A. Spacing-Nitrogen-Variety Interactions
IV. General Considerations
V. Conclusions
265
266
266
269
272
276
277
278
278
281
283
xix
CONTENTS
284
285
VI. Acknowledgments
Literature Cited
13
Discussion
PETER R. JENNINGS
286
Discussion
WERNER L. NELSON
287
Development, Differentiation, and Yield
291
JOHN HESLOP-HARRISON
I. Introduction: Features of the Developmental Process
in Plants .
II. Storage Tissues: Characteristics and Development.
A. Biological Role of Storage Organs .
B. Development of Storage Structures.
C. The Hormonal Factors.
D. The Nutritional Factors
II. Growth, Differentiation, and Translocation.
IV. Differentiation and the Components of Yield
V. The Outlook
Literature Cited
14
291
296
298
299
301
304
305
307
314
316
Discussion
NORMAN E. GOOD
321
Discussion
WALTER E. LOOMIS
324
Cultural Manipulation for Higher Yields
327
WILLIAM G. DUNCAN
I. Introduction
II. Intraspecific Competition
A. Cooperative Interaction
B. Competitive Interaction
C. Plant Uniformity and Barrenness
D. Planting Patterns
E. Tillering .
F. Leaf Area Index
III. No-Tillage Planting
A. Rooting Patterns
B. Future of No-Tillage
IV. Utilization of the Growing Season
A. Ideotypes .
B. Double Cropping
V. Future Research
Literature Cited
327
327
329
329
330
332
333
333
334
335
336
337
337
338
338
339
Discussion
HARRY F. CLEMENTS
339
Discussion
E.B.TREGUNNA
341
CONTENTS
xx
15
Environmental Manipulation for Higher Yields
343
PAUL E. WAGGONER
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
16
Introduction
The Photosynthesis Simulator
The Running of the Simulators .
The Standard Case.
Managing Stomata.
Manipulating Light.
Modifying the Wind
Fertilizing with Carbon Dioxide
Summary .
Literature Cited
343
344
350
355
356
359
362
365
369
370
Germ Plasm Manipulation of the Future
375
G. F.SPRAGUE
I.
II.
III.
IV.
V.
376
378
382
382
382
386
The Transfer of Genetic Information
Enzymes and Heterosis
Mineral Nutrition and Genetics.
Plant Design and Biological Efficiency.
The Physiological Genetics Approach
Literature Cited
Discussion
SUBJECT INDEX
N. F. JENSEN
387
391